A collection of 25 manuscript volumes formerly belonging to John Davies ('Gwyneddon') and his son Alderman Gwyneddon Davies of Caernarfon, the donor. Nineteen of the volumes (Gwyneddon mss 1-16, 19, 23 and 24) were at one time in the possession of the Rev. Peter Bayly Williams, rector of Llanrug and Llanberis, 1792-1836, and of these, the first four, written during the late sixteenth and early seventeenth centuries, are the nucleus of the collection. They contain transcripts of 'cywyddau' and other poems by: Arthur ab Urthur, Bedo Brwynllys, Bedo Aeddren, Bedo ap Phylip Bach, Bleddyn Fardd, Cynddelw, Cynfrig ap Dafydd Goch, Dafydd ap Dafydd Llwyd ab Ieuan ab Owain, Dafydd Ddu o Hiraddug, Dafydd ab Edmwnd, Dafydd ap Gwilym, Dafydd Fynglwyd, Dafydd ap Hywel ap Hywel ab Ieuan Fychan, Dafydd ap Llywelyn ap Madog, Dafydd Llwyd ap Llywelyn ap Gruffudd, Dafydd Nanmor, (Syr) Dafydd Owain, Dafydd ap Siencyn Fynglwyd, Dafydd Trefor, Deio ab Ieuan Du, Edward Morus, Edward ap Raff, Edward ap Rhys, Edward Urien, Einion Offeiriad, Eos Glyn Teifi, (Syr) Gruffudd Fain ap Llywelyn, Gruffudd Gryg, Gruffudd Hiraethog, Gruffudd ab Ieuan ap Llywelyn Fychan, Gwilym ab Ieuan Hen, Gruffudd Llwyd ap Dafydd ab Einion Llygliw, Gutun Goch Brydydd, Guto'r Glyn, Gutun Owain, Gwalchmai, Hywel Cilan, Hywel Dafydd ab Ieuan ap Rhys, Hywel ap Dafydd Llwyd, Hywel ab Einion, Hywel ap Syr Mathew, Huw Arwystli, Huw Cae Llwyd, Huw ab Elise, Huw Llyn, Huw Llwyd ap Hywel ap Rhys, Huw Machno, Iorwerth Fynglwyd, Ieuan Bedo Gwyn, Ieuan Brydydd Hir, Ieuan Clywedog, Ieuan Deulwyn, Ieuan Dyfi, Ieuan Fychan ab Ieuan ab Adda, (Syr) Ieuan o Garno, Ieuan Heiliarth, Ieuan ap Hywel Swrdwal, Ieuan Johns (?Ieuan ap Sion), Ieuan Llwyd Tudur, Ieuan ap Morgan Iorwerth, Ieuan ap Rhydderch ab Ieuan Llwyd, Ieuan Tew Brydydd Hen, Iolo Goch, Lewis Glyn Cothi, Lewis Mon, Lewis Morgannwg, Lewis Trefnant, Llywelyn Goch ap Meurig Hir, Llywelyn ap Hywel ab Ieuan ab Gruffudd, Llywelyn ap Maredudd ab Edward, Llywelyn ap y Moel, Llawdden, Mastr Harri, Mathew Brwmffild, Meilir Brydydd, Maredudd ap Rhys, Morgan ap Huw Lewis, Morus Berwyn, Morus ap Hywel, Owain Gwynedd, Owain ap Llywelyn ap Moel o'r Pantri, Rhisiart ap Hywel o'r Hengaer, Rhisiart Phylip, Robin Ddu, Robert ab Ieuan ap Thomas, Rhys Cain, Rhys Goch Eryri, Rhys Nanmor, Rhys Tegannwy, Siams Dwnn, Siencyn Fynglwyd, Sion Brwynog, Sion ap Dafydd ap Siencyn, Sion Phylip, Sion ap Hywel, Sion Cent, Sion Ceri, Sion Tudur, Sypyn Cyfeiliog, Taliesin Ben Beirdd, Thomas Derllys, Thomas John o Dregaron, Thomas Penllyn, Tudur Aled, Wiliam Egwad, Wiliam Cynwal, Wiliam Llyn and William Midleton.
Gwyneddon mss 5-16 are for the most part written in the hand of Peter Bayly Williams, and contain, apart from some miscellaneous matter, including pedigrees, triads, proverbs, lists of place-names, birds and fishes etc., further transcripts of poems by the bards already mentioned and in addition by: Lewis ab Edward, Llywelyn ap Gutun, Llwydiarth, Ieuan Tew Brydydd o Gydweli, Morus Dwyfech, Huw ap Rhisiart ap Sion, Syr Owain ap Gwilym, curate of Tal-y-llyn, Huw Pennant, Simwnt Fychan, Huw Lewis, Ieuan Waed Da, Syr Dafydd Laes, alias Penllyn, Gruffudd ap Dafydd ap Hywel, William Salesbury, Morgan ap Rhys, Gruffudd Dwnn, Dafydd Gorlech, Sion Rhydderch, John Owen, Rowland Vaughan, Wiliam Phylip, Richard Lloyd, Sion Cain, Rhys Jones o'r Blaenau, Llywelyn Goch y Dant, Gruffudd ap Dafydd Fychan, Hywel Eryri (Hywel Garmon), Gwion Bach, Goronwy Owen, Mabelaf ap Llywarch, Robin Ddu Ieuaf, o Fon, William Wynn o Langynhafal, Sion Powel, Rhisiart Jones o Drefdraeth, Dafydd Ddu Eryri, Llywelyn ap Maredudd ab Ednyfed ab Elise, Bribwll Llanfyrnach, Edward Richard, Rhosier Edward, Iorwerth ab Ioan, Lewis Daron, Hywel ap Rheinallt, Rhys Goch ap Dafydd, Gwilym ap Sefnyn, Dafydd Pennnant, Ieuan Tew Ieuaf , Dafydd Ionawr, William Williams, Llandygai, Griffith Williams ('Gutyn Peris'), Margaret Davies, Ellis Rowland, Griffith Parry, Rowland Ellis, Huw Llwyd o Gynfal, Huw Evans ('Hywel Eryri'), Lewis Owain o Dyddyn y Garreg and Syr Rhys o'r Drewen.
Gwyneddon mss 17 and 18 are commonplace books, the one belonging to the Rev. John Griffith, rector of Llaniestyn in Llyn, with entries ranging from 1732-1751, and the other to an anonymous Dublin lawyer with considerable Welsh connections and covering the period 1682-1688.
Gwyneddon ms 19 consists of transcripts, mostly in the hand of David Ellis, curate of Amlwch in 1776, of 'englynion' by some of the poets previously mentioned as well as by John Vaughan, Cae'r Gai; Thomas Lloyd, Griffith Phylip, Robert Pritchard o Bentraeth, Dafydd Sion, Owen Griffith, Edmwnd Prys, Griffith Bodwrda, Richard Hughes (Cefnllanfair), Gruffudd Peilyn, Thomas Anwyl, Edward Evans, Huw Huws, Mathew Owen, Sion Dafydd (Penllyn), Huw Roberts, Hwmffre Dafydd ab Ieuan, Huw ab Ifan, Ieuan Llwyd Sieffre, Raff ap Robert, Gruffudd Parry, Robert Williams, John Eutyn, Rhys Ionor, Syr Rowland Williams, Robert Hughes, William Davies, Edward Maelor, Rowland Meredith, Dafydd Ellis, Sion Wyn ap Hwmffre, Sion Roger, Rhys Parry, William Elias Rhys Meigen, Ieuan Gruffudd Leiaf, Dr John Davies (Mallwyd) Owain ap Gwilym, Evan James, Casnodyn Fardd, Ednyfed Fychan and Ieuan Iago.
Gwyneddon mss 20, 21 and 22 are all three in the hand of John Davies ('Gwyneddon'), the first two containing minutes, transactions and accounts of two Bangor Welsh literary societies, Cymdeithas Gymroaidd Bangor and Cymdeithas Gomeryddion Bangor for the years 1846-1850, and the third consisting of an essay entitled 'Y Dosbarth Gweithiol yng Nghymru. . .' submitted by J. D. to the Aberystwyth National Eisteddfod of 1865.
Of the three remaining items, Gwyneddon 23, entitled 'Theocriti Idyllia et Epigrammata - Bandi Epistolae Ellenihai', is in Greek script and written by the Rev. Evan Evans ('Ieuan Brydydd Hir'); Gwyneddon ms 24, entitled 'Basgedaid o Friwsion', is a miscellany and scrap-book containing sections from Welsh and English carols, examples of the handwriting of Peter Bayly Williams, letters, etc.; while Gwyneddon ms 25 is a volume (incomplete) of notes of sermons preached at chalcombe, Northants, between 1587 and 1601, probably by the Rev. John Rogers who was vicar there from 1587 to 1632.